Drinking water that contains algae can
have disagreeable tastes and odors.
Because many algae contain significant
quantities of taste- and odor-causing
compounds and toxins within their
cells, it is preferable to remove algae intact
rather than through cell lysis. In addition,
to avoid frequent filter clogging and to
minimize disinfection byproduct concentrations,
it is preferable to remove the algae
prior to the filtration and disinfection steps
of the water treatment process.
Intact algae cells can be removed by
coagulation, flocculation, and sedimentation.
However, coagulation processes are
frequently disrupted by the presence of
algae because raw water pH tends to
increase during algae blooms and because
algae can excrete polysaccharides that
increase coagulant demand. Therefore,
utilities require strategies for the effective
coagulation of algae.
The authors discuss their findings of
optimizing coagulant dosing by means of
charge titrations. They maintain that online
coagulant dose control, via online streaming
current measurements, will allow utilities
to maintain proper coagulant doses
when raw water algae concentrations
and/or background water quality vary.
In optimizing coagulation conditions,
the following factors were evaluated:
streaming current value, coagulation
pH, and initial algae concentration.
Experiments were performed with both
laboratory-cultured Anabaena flos-aquae
that were spiked into a natural water and
a natural algae bloom water that contained
primarily Anabaena spp. and
Synedra spp. Includes 52 references, tables, figures.
| Edition : | Vol. 94 - No. 2 |
| File Size : | 1
file
, 480 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 02/01/2002 |
